Surface topography measurement systems

ABSTRACT

A topographical measurement system uses an imaging cartridge formed of a rigid optical element and a clear, elastomeric sensing surface configured to capture high-resolution topographical data from a measurement surface. The imaging cartridge may be configured as a removable cartridge for the system so that the imaging cartridge, including the rigid optical element and elastomeric sensing surface can be removed and replaced as a single, integral component that is robust/stable over multiple uses, and easily user-replaceable as frequently as necessary or desired. The cartridge may also usefully incorporate a number of light shaping and other features to support optimal illumination and image capture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage entry application of InternationalPatent Application No. PCT/US18/21217 filed on Mar. 6, 2018, whichclaims priority to U.S. Prov. App. No. 62/467,783 filed on Mar. 6, 2017,where the entire contents of each of the foregoing are incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure generally relates to improvements for surfacetopography measurement systems that use a clear elastomer with areflective coating to capture topographical images of a target surface,and more specifically to a removable cartridge for use with suchsystems.

BACKGROUND

One type of high-resolution system for measuring surface topography usesa clear elastomer with a reflective coating disposed on a rigid opticalsubstrate. While such systems usefully permit many types of accurate,detailed surface measurements, the elastomer can delaminate and becomedamaged over the course of multiple uses. At the same time, replacingthe elastomer is error prone, and can be challenging for end users ofsuch systems. There remains a need for improved surface topographymeasurement systems that facilitate rapid and convenient elastomerchanges by end users.

SUMMARY

A topographical measurement system uses an imaging cartridge formed of arigid optical element and a clear, elastomeric sensing surfaceconfigured to capture high-resolution topographical data from ameasurement surface. The imaging cartridge may be configured as aremovable cartridge for the system so that the imaging cartridge,including the rigid optical element and elastomeric sensing surface canbe removed and replaced as a single, integral component that is robustand stable over multiple uses, and easily replaceable by end users. Thecartridge may also usefully incorporate a number of light shaping andother features to support optimal illumination and image capture.

In one aspect, a device disclosed herein includes an optical elementhaving an interior including a rigid, optically transparent material, afirst surface of the optical element, the first surface including aregion with an optically transparent surface for capturing imagesthrough the optical element, a second surface of the optical elementopposing the first surface, a center axis of the optical element passingthrough the first surface and the second surface, a layer of opticallytransparent elastomer disposed on the second surface and attached to thesecond surface, a first side of the layer adjacent to the second surfaceof the optical element having a second index of refraction matched to afirst index of refraction of the second surface, and a second side ofthe layer opposing the second surface of the optical element having anoptical coating with a predetermined reflectance, a sidewall around theinterior of the optical element between the first surface to the secondsurface, the sidewall including one or more light shaping featuresconfigured to control an illumination of the second surface through thesidewall, and a mechanical key on an exterior of the optical element forenforcing a predetermined position of the optical element within afixture of an imaging system, the mechanical key including at least oneradially asymmetric feature about the center axis for enforcing a uniquerotational orientation of the optical element within the fixture of theimaging system.

The mechanical key may include one or more magnets. The mechanical keymay include a plurality of protrusions including at least one protrusionhaving a different shape than other ones of the plurality of protrusionsfor enforcing the unique rotational orientation of the optical elementwithin the fixture of the imaging system. The mechanical key may includethree protrusions shaped and sized to form a kinematic coupling with thefixture of the imaging system. The mechanical key may include a flange.The mechanical key may include a dovetail. The sidewall may include acontinuous surface forming a frustoconical shape with the first surfaceand the second surface. The sidewall may include a continuous surfaceforming a truncated hemisphere with the first surface and the secondsurface. The sidewall may include two or more discrete planar surfaces.The one or more light shaping features may include a diffusing surfaceto diffuse point sources of incoming light along the sidewall. The oneor more light shaping features may include a polished surface to refractincoming light. The one or more light shaping features may include acurved surface to focus incident light. The one or more light shapingfeatures may include a neutral density filter with graduated attenuationto compensate for a distance from the sidewall on the second surface.The one or more light shaping features may include one or more colorfilters. The one or more light shaping features may include a non-normalangle of the sidewall to the second surface. The one or more lightshaping features may include a geometric feature. The one or more lightshaping features may include an optical film. The one or more lightshaping features may include a micro-lens array. The one or more lightshaping features may include a plurality of micro-replicated opticalfeatures. The layer of optically transparent elastomer may be attachedto the second surface through a retaining structure. The retainingstructure may include an index-matched optical adhesive disposed betweenthe layer of optically transparent elastomer and the second surface ofthe optical element. The retaining structure may include a retainingring about a perimeter of the layer of optically transparent elastomermechanically securing the perimeter to the second surface. The retainingstructure may include a recess within the second surface of the opticalelement and a corresponding protrusion in the first side of the layer ofoptically transparent elastomer that extend into the recess. The recessmay include a groove. The recess may be dovetailed to provide a widerregion away from the second surface. The optically transparent elastomermay be liquid-formed into the recess. The optically transparentelastomer may be thermoformed into the recess. The second surface of theoptical element may include a convex curved surface extending from theoptical element. The second side of the layer of optically transparentelastomer may include a convex curved surface extending away from theoptical element. The rigid, optically transparent material may includeat least one of a glass, a polycarbonate, and an acrylic. The device mayfurther include one or more magnets to secure the device in the fixtureof the imaging system. The imaging system may include a camera and oneor more light sources in a predetermined geometric configurationrelative to the fixture. The device may further include a robotic systemconfigured to automatically remove the device from the fixture of theimaging system. The robotic system may be further configured to insert asecond device into the fixture of the imaging system. The robotic systemmay include at least one magnet. The robotic system may include anelectromechanical latch. The first surface may include a curved surfaceproviding lens to optically magnify an image from the second surface forthe imaging system. The first surface may include an aspheric surfaceshaped to address optical aberrations in an image captured through theoptical element from the second surface. The first surface may include afreeform surface shaped to mitigate geometric distortion in an imagecaptured through the optical element from the second surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of devices, systems, and methods described herein are shownin the following drawings. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating the principles of thisdisclosure.

FIG. 1 shows an imaging system.

FIG. 2 shows a cross-section of an imaging cartridge for an imagingsystem.

FIG. 3 shows a top view of an imaging cartridge.

FIG. 4 is a perspective view of an optical element and a housing for animaging system.

FIG. 5 is a side view of an optical element for an imaging system.

FIG. 6 is a perspective view of an optical element.

FIG. 7 is a perspective view of an optical element.

FIG. 8 is a perspective view of an optical element.

FIG. 9 is a perspective view of an optical element.

FIG. 10 is a side view of the optical element of FIG. 9.

FIG. 11 shows a robotic system using an imaging cartridge.

DETAILED DESCRIPTION

All documents mentioned herein are incorporated by reference in theirentirety. References to items in the singular should be understood toinclude items in the plural, and vice versa, unless explicitly statedotherwise or clear from the context. Grammatical conjunctions areintended to express any and all disjunctive and conjunctive combinationsof conjoined clauses, sentences, words, and the like, unless otherwisestated or clear from the context. Thus, the term “or” should generallybe understood to mean “and/or” and so forth.

Recitation of ranges of values herein are not intended to be limiting,referring instead individually to any and all values falling within therange, unless otherwise indicated herein, and each separate value withinsuch a range is incorporated into the specification as if it wereindividually recited herein. The words “about,” “approximately,” or thelike, when accompanying a numerical value, are to be construed asindicating a deviation as would be appreciated by one of ordinary skillin the art to operate satisfactorily for an intended purpose. Ranges ofvalues and/or numeric values are provided herein as examples only, anddo not constitute a limitation on the scope of the describedembodiments. The use of any and all examples, or exemplary language(“e.g.,” “such as,” or the like) provided herein, is intended merely tobetter illuminate the embodiments and does not pose a limitation on thescope of the embodiments or the claims. No language in the specificationshould be construed as indicating any unclaimed element as essential tothe practice of the embodiments.

In the following description, it is understood that terms such as“first,” “second,” “top,” “bottom,” “up,” “down,” and the like, arewords of convenience and are not to be construed as limiting termsunless specifically stated to the contrary.

The devices, systems, and methods described herein may include, or maybe used in conjunction with, the teachings of U.S. patent applicationSer. No. 14/201,835 filed on Mar. 8, 2014, U.S. Pat. No. 9,127,938granted on Sep. 8, 2015, and U.S. Pat. No. 8,411,140 granted on Apr. 2,2013. The entire contents of each of the foregoing is herebyincorporated by reference. In certain aspects, the devices, systems, andmethods described herein may be used to provide readily interchangeableimaging cartridges for handheld or quantitative topographical orthree-dimensional measurement systems. However, the devices, systems,and methods described herein may also or instead be included on, orotherwise used with, other systems. For example, the systems describedherein may useful for, e.g., robotic end effector systems, such as forpart identification and pose estimation, force feedback, roboticsurgery, medical examination, and the like as well as other systems andapplications where one or more of touch, tactile sensing, surfacetopography, or three-dimensional measurements are necessary or helpful.

FIG. 1 shows an imaging system. In general, the imaging system 100 maybe any system for quantitative or qualitative topographicalmeasurements, such as any of those described in the documents identifiedabove. The imaging system 100 may include an imaging cartridge 102configured as a removable and replaceable cartridge for the imagingsystem 100, along with a fixture 104 for retaining the imaging cartridge102. The fixture 104 may have a predetermined geometric configurationrelative to the imaging system 100, e.g., relative to an imaging device106 such as a camera and an illumination source 108 such as one or morelight emitting diodes or other light sources, so that the imagingcartridge 102, when secured in the fixture 104, has a known position andorientation relative to the camera and light source(s). This enforcedgeometry advantageously permits re-use of calibration data for animaging cartridge 102, and reliable, repeatable positioning of theimaging cartridge 102 within an optical train of the imaging system 100.

The imaging cartridge 102 may include an optical element 110 formed atleast in part of a rigid, optically transparent material such as glass,polycarbonate, acrylic, polystyrene, polyurethane, an opticallytransparent epoxy, and so forth. A silicone may also be used, such as ahard platinum cured silicone. As a further advantage, the layer 116 ofoptically transparent elastomer may be formed from a soft platinum curedsilicone and bonded to the hard silicone without the use of adhesives.Thus, in one aspect, the optical element 110 and the layer 116 may beformed of materials that facilitate direct bonding without any use ofadhesives. The optical element 110 may include a first surface 112including a region with an optically transparent surface for capturingimages through the optical element 110, e.g., by the imaging device 106.The optical element 110 may also include a second surface 114 opposingthe first surface 112, with a center axis 117 passing through the firstsurface 112 and the second surface 114.

In general, the first surface 112 may have optical properties suitablefor conveying an image from the second surface 114 through the opticalelement 110 to the imaging device 106. To support this function, thefirst surface 112 may, for example, include a curved surface providing alens to optically magnify an image from the second surface 114. Inanother aspect, the first surface 112 may include an aspheric surfaceshaped to address spherical aberrations or other optical aberrations inan image captured through the optical element 110 from the secondsurface 114. The first surface 112 may also or instead include afreeform surface shaped to reduce or otherwise mitigate geometricdistortion in an image captured through the optical element 110. Imagingthrough a thick media may generally lead to spherical aberration with amagnitude depending on a numerical aperture of the imaging system 100(or more specifically here, the optical element 110). Thus, the firstsurface 112 of the optical element 110 may be curved or otherwiseadapted to address such spherical aberrations resulting from imagepropagation through thick media. More generally, the first surface 112may include any shape or surface treatment suitable to focus, shape, ormodify the image in a manner that supports capture of topographical datausing the optical element 110. The second surface 114 may also orinstead be modified to improve image capture. For example, the secondsurface 114 of the optical element 110 may include a convex surfaceextending from the optical element 110 (e.g., toward the target surface130 being imaged) in order to magnify or otherwise shape an imageconveyed from the target surface 130 to the imaging device 106.

The optical element 110 may generally serve a number of purposes in animaging system 100 as contemplated herein. In one aspect, the opticalelement 110 serves as a rigid body to transfer pressure relativelyuniformly across a target surface 130 when capturing images.Specifically, the body of the optical element 110 may apply asubstantially uniform pressure on a clear substrate gel such that areflective membrane coating on the other side of the clear substrateconforms to the measured surface topography. The optical element 110 mayalso or instead provide directional dark field illumination. To thisend, sufficiently thick optical material may function as a light guideto provide controlled, uniform, and close to collimated dark fieldillumination of the reflective membrane surface from distinct directions(e.g., when one LED segment of the illumination source 108 is on) orfrom all around (e.g., when all LED segments of the illumination source108 are on).

A layer 116 of optically transparent elastomer may be disposed on thesecond surface 114 and attached to the second surface 114 using anysuitable means, such as any of those described herein. In general, thelayer 116 may be formed of a gel or other relatively pliable materialthat is capable of deforming to match a topography of a target surface130 so that the complementary shape formed in the layer 116 can beoptically captured through an opposing surface of the layer 116. Interms of pliability, an elastomer with a Shore 00 durometer value ofabout 5-60 may usefully serve as the layer 116 contemplated herein. Ingeneral, a first side 118 of the layer 116 that is adjacent to thesecond surface 114 of the optical element 110 may have an index ofrefraction that is matched to the index of refraction of the secondsurface 114. It will be appreciated that, as used herein when referringto indices of refraction, the term “matched” does not require identicalindices of refraction. Instead, the term “matched” generally meanshaving indices of refraction that are sufficiently close to transmitimages through a corresponding interface between two materials forcapture by the imaging device 106. Thus, for example, acrylic has anindex of refraction of about 1.49 while polydimethylsiloxane has anindex of refraction of about 1.41 and these materials are sufficientlymatched that they can be placed adjacent to one another and can be usedto transmit images sufficient for quantitative or qualitativetopographical measurements as contemplated herein.

A second side 120 of the layer 116 may be configured to conform to atarget surface 130 while providing a surface facing the imaging device106 that facilitates topographical imaging and measurements by theimaging system 100. The second side 120 may, for example, include anopaque coating, or more generally, any optical coating with apredetermined reflectance suitable for supporting topographical imagingas contemplated herein. In general, this coating can facilitate captureof images through the optical element 110 that are independent ofoptical properties of the target surface 130 such as color,translucence, gloss, specularity, and the like that might otherwiseinterfere with optical imaging. In one aspect, the second side 120 mayinclude a convex surface extending away from the optical element 110(e.g., toward the target surface 130). This geometric configuration canprovide numerous advantages such as facilitating imaging of surfaceswith large, aggregate concave shapes, and mitigating an accumulation ofair bubbles within the field of view when the imaging cartridge 102 isinitially placed in contact with a target surface 130.

A sidewall 122 may be formed around an interior 124 of the opticalelement 110 extending from the first surface 112 to the second surface114. In general, the sidewall 122 may include one or more light shapingfeatures configured to control an illumination of the second surface 114through the sidewall 122, e.g., from the illumination source 108. Thesidewall 122 may assume a variety of geometries with useful lightshaping features, e.g., to steer light at desirable angles anduniformity into and through the optical element 110. For example, thesidewall 122 may include a continuous surface forming a frustoconicalshape between two circles formed in the first surface 112 and the secondsurface 114. The sidewall 122 may also or instead include a truncatedhemisphere between some or all of the region between the first surface112 and the second surface 114. In another aspect, the sidewall 122 mayinclude two or more discrete planar surfaces arranged into a regular orirregular polygonal geometry such as a hexagon or an octagon about thecenter axis 117. In this later embodiment with planar surfaces, eachsuch surface may have an illumination source 108 such as one or morelight emitting diodes adjacent thereto in order to provide side lightingas desired through the optical element 110.

Other light shaping features may also or instead be used with thesidewall 122, e.g., to focus or steer incident light from theillumination source 108, or to control reflection of light within theoptical element 110 and/or the layer 116 of optically transparentelastomer. For example, the light shaping feature may include adiffusing surface to diffuse point sources of incoming light along thesidewall 122. This may, for example, help to diffuse light fromindividual light emitting diode elements in the illumination source 108,and/or to provide a more uniform illumination field from a planarsurface of the sidewall 122. The sidewall 122 may also or insteadinclude a polished surface to refract incoming light into the opticalelement 110. It will be appreciated that diffusing and reflectingsurfaces may also be used in various combinations to generally shapeillumination within the optical element 110. The sidewall 122 may alsoor instead include a curved surface, e.g., forming a lens within thesidewall 122 to focus or steer incident light into the optical element110 as desired.

In another aspect, the sidewall 122 may include a neutral density filterwith graduated attenuation to compensate for a distance from thesidewall 122. More specifically, in order to avoid over-illumination ofregions of the second surface 118 near the sidewall 122, and/orunder-illumination of regions of the second surface 118 away from thesidewall 122 (and closer to the center axis 117), the sidewall 122 mayprovide broadband attenuation with a neutral density filter thatprovides greater attenuation in areas of the sidewall 122 closer to thesecond surface 114 and less attenuation in areas of the sidewall 122closer to the first surface 112. In this manner, light rays directlyilluminating the second surface 114 at a downward angle adjacent to thesidewall 122 may be more attenuated than other light rays exiting theillumination source 108 toward the center of the second surface 114.This attenuation may, for example, be continuous, discrete, or otherwisegraduated to provide generally greater attenuation closer to thesidewall 122 or otherwise balance illumination within the field of view.

In another aspect, the light shaping feature may include one or morecolor filters, which may usefully be employed, e.g., to correlateparticular colors to particular directions of illumination within theoptical element 110, or otherwise control use of colored illuminationfrom the illumination source 108. In another aspect, the light shapingfeature may include a non-normal angle of the sidewall 122 to the secondsurface 114. For example, as illustrate in FIG. 1, the sidewall 122 isangled away from the second surface 114 to form an obtuse angletherewith. This approach may advantageously support indirectillumination of the second surface 118, e.g. by reflecting light off ofthe first surface 112 and into the optical element 110. In anotheraspect, the sidewall 122 may be angled toward the second surface toprovide an acute angle therewith, e.g., in order to support greaterdirect illumination of the second surface 118. These approaches may beused alone or in combination to steer light as desired into and throughthe optical element 110.

The light shaping feature may also or instead include a geometricfeature such as a focusing lens, planar regions, or the like to directincident light as desired. Other optical elements may also or insteadusefully be formed onto or into the sidewall 122. For example, the lightshaping feature may include an optical film such as any of a variety ofcommercially available films for filtering, attenuating, polarizing orotherwise shaping the incident light. The light shaping feature may alsoor instead include a micro-lens array or the like to steer or focusincident light from the illumination source 108. The light shapingfeature may also or instead include a plurality of micro-replicatedand/or diffractive optical features such as lenses, gratings, or thelike. For example, a microstructured sidewall 122 may include, e.g.,microimaging lenses, lenticulars, microprisms, and so on as lightshaping features to steer light from the illumination source 108 intothe optical element 110 in a manner that improves imaging oftopographical variations to the imaging surface of the imaging cartridge102 on the second side 120 of the layer 116 of optically transparentelastomer. For example, microstructured features may facilitate shapingthe illumination pattern to provide uniform light distribution acrossthe measured field, reduce the reflection of light back into or out ofthe optical element 110, and so forth. Microstructuring may, forexample, be imposed during injection molding of the optical element 110,or by applying an optical film with the desired microstructure to theside surface. For example, a commercially suitable optical film includesVikuiti™, an advanced light control film (ALCF) sold by 3M.

A mechanical key 126 may be disposed on an exterior of the opticalelement 110 for enforcing a predetermined position of the opticalelement 110 (and more generally, the imaging cartridge 102) within thefixture 104 of the imaging system 100. The mechanical key 126 may, forexample, include at least one radially asymmetric feature about thecenter axis 117 for enforcing a unique rotational orientation of theoptical element 110 within the fixture 104 of the imaging system 100.The mechanical key 126 may include any number of mechanical elements orthe like suitable for retaining the optical element 110 in apredetermined orientation within the imaging system 100. The mechanicalkey 126 may also or instead include a matched geometry between theoptical element 110 and the fixture 104. For example, the mechanical key126 may include a cylindrical structure extending from the opticalelement 110, or an elliptical prism or the like, which may usefullyenforce a rotational orientation concurrently with position.

In one aspect, the mechanical key 126 may include one or more magnets128, which may secure the optical element 110 in the fixture 104 of theimaging system. The magnets 128 may be further encoded via positioningand/or polarity to ensure that the optical element 110 is only insertedin a particular rotational orientation about the center axis 117. Themechanical key 126 may also or instead include a plurality ofprotrusions including at least one protrusion having a different shapethan other ones of the plurality of protrusions for enforcing the uniquerotational orientation of the optical element 110 about the center axis117 within the fixture 104 of the imaging system 100. The mechanical key126 may also or instead include at least three protrusions (e.g.,exactly three protrusions) shaped and sized to form a kinematic couplingwith the fixture 104 of the imaging system 100. The mechanical key 126may also or instead include features such as a flange, a dovetail, orany other mechanical shapes or features to securely mate the opticalelement 110 to the fixture 104 in a predetermined position and/ororientation. A number of specific mechanical keying systems arediscussed herein with reference to specific optical element designs andconfigurations.

Surfaces of the imaging cartridge 102 may be further treated asnecessary or helpful for use in an imaging system 100 as contemplatedherein. For example, regions of the top, side, and bottom surfaces ofthe optical element 110 or other portions of the imaging cartridge 102may be covered with a light absorbing layer, such as a black paint,e.g., to contain light from the illumination source 108 or to reduceinfiltration of ambient light.

One challenge to securing a flexible elastomer (in the layer 116) to arigid surface such as the optical element 110 may be delamination, whichcan result from shear forces and other edge effects after repeated imagecapture, particularly where the target surface 130 tends to adhere tothe elastomer. To address this issue, the optical element 110 and thelayer 116 of clear elastomer may be formed as a cartridge that isprovided for end users as an integral, removable and replaceable device.This cartridge can be quickly and easily replaced by an end user asrequired, or in order to substitute in an imaging cartridge 102 withdifferent optical properties, e.g., for a different imaging application,resolution, or the like. At the same time, concurrent replacement of theoptical element 110 with the layer 116 permits the use of more robustmeans for mechanically securing the layer 116 of elastomer to theoptical element 110. As a significant advantage, this approach canmitigate challenges to the end user associated with exchanging the layer116 of elastomer, such as the introduction of contaminants or airbubbles between the layer 116 of elastomer and the optical element 110.

FIG. 2 shows a cross-section of an imaging cartridge for an imagingsystem. In general, the imaging cartridge 200 may include a layer 206 ofoptically transparent elastomer coupled to an optical element 204. Thismay include any of the layers of elastomer and optical elementsdescribed herein. In general, the layer 206 of elastomer may be coupledto the optical element 204 using any suitable retaining structure.Because the layer of elastomer and the optical element 204 are providedto end users as an integrated cartridge, as distinguished from similarsystems of the prior art, which required periodic manual replacement ofthe layer 206 of elastomer, a wider variety and combination oftechniques may be used to securely retain the layer 206 adjacent to theoptical element 204.

The retaining structure may include any tackifier or other adhesive,glue, epoxy, or the like, including any of the adhesives describedherein. Where the imaging cartridge 200 is fabricated for use as anintegral, consumable product, it should not generally be necessary toremove and replace the layer 206 of elastomer, and the layer 206 may beaffixed to the optical element 204 with a relatively strong, rigidepoxy. In one aspect, the retaining structure may include anindex-matched optical adhesive disposed between the layer 206 ofoptically transparent elastomer and the surface of the optical element204. As discussed above, index-matched in this context refers to anyindices of refraction sufficiently close to support optical transmissionof a useful image across the corresponding interface.

The retaining structure may also include a retaining ring 208 about aperimeter of the layer 206 of optically transparent elastomermechanically securing the perimeter to the surface of the opticalelement 204. The retaining ring 208 may traverse the entire perimeter orone or more portions of the perimeter. While the retaining ring 208 mayoptionally extend over a top, functional surface of the layer 206 ofelastomer, this may interfere with placement of the imaging cartridge200 on a target surface, particularly if the target surface issubstantially planar. Thus, in one aspect, the retaining ring 208 mayusefully be positioned within an indent 210 or the like formed within anedge of the layer 206, or an indent 210 created by a mechanical force ofthe retaining ring 208 against the more pliable elastomer of the layer206. It will be appreciated that the retaining ring 208 may have anyshape, corresponding generally to a shape of a perimeter of the layer206 of elastomer such as a polygon, ellipse, and so forth. Thus, theterm “ring” as used in this context, is not intended to suggest orrequire a circular or rounded shape. Further, while a retaining ring 208is described, the retaining structure may also or instead include anynumber of tabs, protrusions, flanges, or the like extending over or intothe layer 206 to mechanically secure the perimeter of the layer 206 incontact with the optical element 204.

The retaining structure may also or instead include a recess 212 withinthe surface of the optical element, and a corresponding protrusion 214in the layer 206 of optically transparent elastomer that extends intothe recess 212. The recess 212 may include a groove or other shapesuitable for receiving the protrusion 214. In one aspect, the recess 212may be dovetailed to provide a wider region away from the surface of thelayer 206 in order to improve the mechanical strength of the bond formedbetween the layer 206 of elastomer and the optical element 204. Moregenerally, the recess 212 may be structurally configured to retain thelayer 206 on the surface of the optical element 204. In this manner, amechanical coupling may be formed between the layer 206 and the opticalelement 204, e.g., to replace or augment a coupling formed by adhesives,a retaining ring 208, or any other retaining structures.

In order to fill the recess 212 during manufacturing, the layer 206 ofelastomer may be liquid-formed or thermo-formed into the recess 212using any suitable, optically transparent elastomer. Suitably shaped,deformable elastomers may also or instead be press-fit or otherwiseassembled into the recess 212. However, by applying the elastomer as aliquid and then curing the elastomer, the layer 206 of elastomer maymore fully fill the void space of the recess 212 and provide a strongermechanical bond to the optical element 204.

FIG. 3 shows a top view of an imaging cartridge. The imaging cartridge300 may be an imaging cartridge such as any of the imaging cartridges orsimilar components described herein. In general, the imaging cartridge300 may include a layer 302 of a pliable elastomer used to contact andcapture images of target surfaces. The layer 302 may be secured to anoptical element through a variety of retaining structures such as aretaining ring 304 about a perimeter 306 of the layer 302, or aprotrusion 308 formed into a recess in the optical element. In general,the imaging cartridge 300 and/or layer 302 may have any of a variety ofshapes. For example, the layer 302 may include a perimeter 306 in theshape of a circle, an ellipse, a square, a rectangle, or any otherpolygon or other shape.

A variety of imaging cartridges incorporating features described hereinwill now be described.

FIG. 4 is a perspective view of an optical element and a housing for animaging system. The optical element 402 may, for example, be any of theoptical elements 402 described herein. In general, the optical element402 may include a number of protrusions 404, 406, which may be axiallyasymmetric in order to enforce a unique radial orientation within thehousing 408. For example, one protrusion 406 may be larger than theother protrusions 404 in order to provide radial keying, or theprotrusions 406 may be irregularly spaced in a manner that enforces aunique radial orientation, or some combination of these. The housing 408may include a number of slots 410 or the like to receive the protrusions406, 408, after which the optical element 402 may be rotated about anaxis 412 of the imaging system 400 so that the protrusions 406, 408securely retain the optical element 402 within the housing 408. Theprotrusions 406, 408 may, for example, form a kinematic coupling withthe slots 410 of the housing 408 to enforce a predetermined geometricorientation of the optical element 402 within the housing 408 and anassociated imaging system.

FIG. 5 is a side view of an optical element for an imaging system. Itwill be noted that, in the embodiment of FIG. 5, a top surface 502 ofthe optical element 504 extends above a number of protrusions 506 thatsecure the optical element 504 to a housing. This permits a layer of anelastomer to extend beyond the surface of the housing sufficiently sothat the housing does not interfere with contact between the elastomericlayer and a target surface. As described above, a layer of transparentelastomer (not shown) may be affixed to the surface of the opticalelement 504 using any suitable techniques.

The imaging cartridge may have a variety of different shapes, and mayusefully share a mounting interface such as protrusions so thatdifferent types of imaging cartridges can be used within the samehousing for different imaging applications. FIG. 6 is a perspective viewof an optical element 602 having a low profile. The optical element 602may be shaped and sized to fit securely within a housing such as thehousing 408 of FIG. 4, but may be thinner, e.g., to reduce opticalaberrations in images captured through the optical element 602 or tofacilitate the use of additional optical elements such as filters,imaging lenses, and the like between the optical element 602 and acamera or other imaging device of an imaging system. This profile canalso advantageously accommodate lighting through the surface 604 facinga camera (and opposing an elastomer layer and target surface) tofacilitate illumination and imaging of high-aspect negative features onthe target surface such as trenches, deep grooves, and the like. In thiscontext, the term “high-aspect” is intended to refer to features thatare (or might be) occluded from illumination at grazing illuminationangles of, e.g., more than forty-five degrees from the surface normal.

FIG. 7 is a perspective view of an optical element. The optical element702 may include a convex surface 704 shaped to support an elastomerlayer in a manner that extends away from the optical element 702, whichmay advantageously permit imaging of relatively concave surfaces, andmay also advantageously mitigate bubble formation when the elastomerlayer is placed on a target surface for image capture. The opticalelement 702 may be shaped and sized to fit securely within a housingsuch as the housing 408 of FIG. 4.

FIG. 8 is a perspective view of an optical element. The optical element802 may usefully incorporate a high-profile contact surface 804 thatextends away from the protrusions 806 of the optical element 802, e.g.,to provide greater clearance between a housing and the imaging surface.The optical element 802 may be shaped and sized to fit securely within ahousing such as the housing 408 of FIG. 4. In general, the foregoingoptical elements may be used interchangeably with a single housing, thusfacilitating different modes of operation supported by different imagingcartridge properties. Further, by providing a kinematic coupling orsimilarly orientation-specific mounting system, calibration results andthe like for a particular optical element may be recalled and reusedwhen a previously used optical element is once again placed within thehousing.

FIG. 9 is a perspective view of an optical element. The optical element902 may, for example, have a generally rectangular construction, and mayinclude one or more flanges 904 or the like so that the optical element902 can linearly slide into engagement with a fixture of a housing. Thistype of engagement mechanism may be particularly suited to roboticapplications or the like, such as where the optical element 902 isremoved from and replaced to an end effector of a robotic arm. Theoptical element 902 may, for example, be any of the optical elementsdescribed herein, with corresponding surface and sidewall properties. Alayer 906, such as any of the layers of optically transparent elastomerdescribed herein, may be disposed on the optical element 902 to providea contact surface for capturing topographical images of a targetsurface. The layer 906 may be convex, or otherwise curved away from theoptical element 902, e.g., to provide clearance from a housing and/or tomitigate formation of air bubbles when the layer 906 is placed for useon a target surface. FIG. 10 is a side view of the optical element ofFIG. 9.

FIG. 11 shows a robotic system using an imaging cartridge. In general,the system 1100 may include a robotic arm 1102 coupled to a housing 1104configured to removably and replaceably receive a cartridge 1106 such asany of the imaging cartridges or other optical devices described herein.The robotic arm 1102 (or any other suitable robotic element(s)) may beconfigured to position the cartridge 1106 in contact with a targetsurface 1108 in order to capture topographical images of the targetsurface 1108 through the cartridge 1106 using, e.g., a camera or otherimaging device in the housing 1104. In general, the system 1100 may beconfigured to automatically remove the cartridge 1106 from a fixture ofthe imaging system 1100 (e.g., in the housing 1104), and to insert asecond cartridge 1110 into the housing 1104. The second cartridge 1110may be the same as the cartridge 1106, e.g., to provide a replacementafter ordinary wear and tear, or the second cartridge 1110 may have adifferent optical configuration than the first cartridge 1106, e.g., toprovide greater magnification, a larger field of view, better featureresolution, deep feature illumination, different aggregate surfaceshape, different shape tolerances for the target surface 1108, and soforth. The second cartridge 1110 may be stored in a bin or otherreceptacle accessible to the robotic arm 1102 of the system 1100. Ingeneral, the system 1100 may include one or more magnets,electromechanical latches, actuators, and so forth, within the housing1104, or more generally within the system 1100, to facilitate removaland replacement of the cartridge 1106 as described herein. Moregenerally, the system 1100 may include any gripper, clamp, or otherelectromechanical end effector or the like suitable for removing andreplacing the cartridge 1106 and positioning the cartridge 1106 for usein an imaging process.

The above systems, devices, methods, processes, and the like may berealized in hardware, software, or any combination of these suitable fora particular application. The hardware may include a general-purposecomputer and/or dedicated computing device. This includes realization inone or more microprocessors, microcontrollers, embeddedmicrocontrollers, programmable digital signal processors or otherprogrammable devices or processing circuitry, along with internal and/orexternal memory. This may also, or instead, include one or moreapplication specific integrated circuits, programmable gate arrays,programmable array logic components, or any other device or devices thatmay be configured to process electronic signals. It will further beappreciated that a realization of the processes or devices describedabove may include computer-executable code created using a structuredprogramming language such as C, an object oriented programming languagesuch as C++, or any other high-level or low-level programming language(including assembly languages, hardware description languages, anddatabase programming languages and technologies) that may be stored,compiled or interpreted to run on one of the above devices, as well asheterogeneous combinations of processors, processor architectures, orcombinations of different hardware and software. In another aspect, themethods may be embodied in systems that perform the steps thereof, andmay be distributed across devices in a number of ways. At the same time,processing may be distributed across devices such as the various systemsdescribed above, or all of the functionality may be integrated into adedicated, standalone device or other hardware. In another aspect, meansfor performing the steps associated with the processes described abovemay include any of the hardware and/or software described above. Allsuch permutations and combinations are intended to fall within the scopeof the present disclosure.

Embodiments disclosed herein may include computer program productscomprising computer-executable code or computer-usable code that, whenexecuting on one or more computing devices, performs any and/or all ofthe steps thereof. The code may be stored in a non-transitory fashion ina computer memory, which may be a memory from which the program executes(such as random access memory associated with a processor), or a storagedevice such as a disk drive, flash memory or any other optical,electromagnetic, magnetic, infrared or other device or combination ofdevices. In another aspect, any of the systems and methods describedabove may be embodied in any suitable transmission or propagation mediumcarrying computer-executable code and/or any inputs or outputs fromsame.

It will be appreciated that the devices, systems, and methods describedabove are set forth by way of example and not of limitation. Absent anexplicit indication to the contrary, the disclosed steps may bemodified, supplemented, omitted, and/or re-ordered without departingfrom the scope of this disclosure. Numerous variations, additions,omissions, and other modifications will be apparent to one of ordinaryskill in the art. In addition, the order or presentation of method stepsin the description and drawings above is not intended to require thisorder of performing the recited steps unless a particular order isexpressly required or otherwise clear from the context.

The method steps of the implementations described herein are intended toinclude any suitable method of causing such method steps to beperformed, consistent with the patentability of the following claims,unless a different meaning is expressly provided or otherwise clear fromthe context. So, for example performing the step of X includes anysuitable method for causing another party such as a remote user, aremote processing resource (e.g., a server or cloud computer) or amachine to perform the step of X. Similarly, performing steps X, Y and Zmay include any method of directing or controlling any combination ofsuch other individuals or resources to perform steps X, Y and Z toobtain the benefit of such steps. Thus, method steps of theimplementations described herein are intended to include any suitablemethod of causing one or more other parties or entities to perform thesteps, consistent with the patentability of the following claims, unlessa different meaning is expressly provided or otherwise clear from thecontext. Such parties or entities need not be under the direction orcontrol of any other party or entity, and need not be located within aparticular jurisdiction.

It should further be appreciated that the methods above are provided byway of example. Absent an explicit indication to the contrary, thedisclosed steps may be modified, supplemented, omitted, and/orre-ordered without departing from the scope of this disclosure.

It will be appreciated that the methods and systems described above areset forth by way of example and not of limitation. Numerous variations,additions, omissions, and other modifications will be apparent to one ofordinary skill in the art. In addition, the order or presentation ofmethod steps in the description and drawings above is not intended torequire this order of performing the recited steps unless a particularorder is expressly required or otherwise clear from the context. Thus,while particular embodiments have been shown and described, it will beapparent to those skilled in the art that various changes andmodifications in form and details may be made therein without departingfrom the spirit and scope of this disclosure and are intended to form apart of the invention as defined by the following claims, which are tobe interpreted in the broadest sense allowable by law.

1-39. (canceled)
 40. A device comprising: an optical element having aninterior including a rigid, optically transparent material; a firstsurface of the optical element, the first surface including a regionwith an optically transparent surface for capturing images through theoptical element; a second surface of the optical element opposing thefirst surface; a center axis of the optical element passing through thefirst surface and the second surface; a layer of optically transparentelastomer disposed on the second surface and attached to the secondsurface, a first side of the layer adjacent to the second surface of theoptical element having a second index of refraction matched to a firstindex of refraction of the second surface, and a second side of thelayer opposing the second surface of the optical element having anoptical coating with a predetermined reflectance; a sidewall around theinterior of the optical element between the first surface to the secondsurface, the sidewall including one or more light shaping featuresconfigured to control an illumination of the second surface through thesidewall; and a mechanical key on an exterior of the optical element forenforcing a predetermined position of the optical element within afixture of an imaging system, the mechanical key including at least oneradially asymmetric feature about the center axis for enforcing a uniquerotational orientation of the optical element within the fixture of theimaging system.
 41. The device of claim 40 wherein the sidewall includesa continuous surface forming a frustoconical shape with the firstsurface and the second surface.
 42. The device of claim 40 wherein thesidewall includes a continuous surface forming a truncated hemispherewith the first surface and the second surface.
 43. The device of claim40 wherein the sidewall includes two or more discrete planar surfaces.44. The device of claim 40 wherein the one or more light shapingfeatures include a diffusing surface to diffuse point sources ofincoming light along the sidewall.
 45. The device of claim 40 whereinthe one or more light shaping features include a polished surface torefract incoming light.
 46. The device of claim 40 wherein the one ormore light shaping features include a curved surface to focus incidentlight.
 47. The device of claim 40 wherein the one or more light shapingfeatures include a neutral density filter with graduated attenuation tocompensate for a distance from the sidewall on the second surface. 48.The device of claim 40 wherein the one or more light shaping featuresinclude one or more color filters.
 49. The device of claim 40 whereinthe one or more light shaping features include a non-normal angle of thesidewall to the second surface.
 50. The device of claim 40 wherein theone or more light shaping features include a geometric feature.
 51. Thedevice of claim 40 wherein the one or more light shaping featuresinclude an optical film.
 52. The device of claim 40 wherein the one ormore light shaping features include a micro-lens array.
 53. The deviceof claim 40 wherein the one or more light shaping features include aplurality of micro-replicated optical features.
 54. The device of claim40 wherein the first surface includes a curved surface providing lens tooptically magnify an image from the second surface for the imagingsystem.
 55. The device of claim 40 wherein the first surface includes anaspheric surface shaped to address optical aberrations in an imagecaptured through the optical element from the second surface.
 56. Thedevice of claim 40 wherein the first surface includes a freeform surfaceshaped to mitigate geometric distortion in an image captured through theoptical element from the second surface.
 57. The device of claim 40wherein the mechanical key includes one or more magnets.
 58. The deviceof claim 40 wherein the mechanical key includes a plurality ofprotrusions including at least one protrusion having a different shapethan other ones of the plurality of protrusions for enforcing the uniquerotational orientation of the optical element within the fixture of theimaging system.
 59. The device of claim 40 wherein the mechanical keyincludes three protrusions shaped and sized to form a kinematic couplingwith the fixture of the imaging system.